Process of removing impurities from vegetable oils



Sept. 24, 1940. G. J. STREZYNSKI 2,215,624

PROCESS OF REMOVT NG IMPURITI'ES FROM VEGETABLE OILS Filed July 16, 1937COOK 5:?

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Patented Sept. 24, 1940 (PATENT OFFICE} rnoonss F REMOVING IMPURITIESFROM w VEGETABLE ons- George J L vStrezynski, Poughke'epsie, N. Y.,assignor to The De Laval Separator Company, New York, N. Y.,' acorporation of New Jersey Application my, 16, 1937, Serial No. 153,901

B'Claims. (01. 260 -428) My invention is an improved process-forpurifying vegetable oils, such as cottonseed oil, which, as they comefrom the press, contain considerable meal, someof which is coarse andsettles out 5' quickly while a smaller quantityof finer meal settlesvery slowly. Such fine meal is not heavy enough to enable its separationto be centrifugally effected, nor would it be fluid enough if itsseparation could be effected to flow outof the bowl.

If, however, water is added to the oil, it will be absorbed by the mealand gravity or centrifugal subsidence is possible. But gravitysettlement is impracticable, because the water soon enters into,

chemical combination with the meal, developing acids which aredeleterious to the oil. I have found, however, that if, after additionto, for example, cottonseed oil, of a small quantity of water,immediately or within a very short time, and before the objectionablereaction has proceeded to a substantial extent, the oil be subjected tocentrifugal separation, separation can be satisfactorily effected. Theseparated oil is brilliantly clear, though it has a small quantity(probably between .1% and 5%) of water in solution.

On standing for 12 or more hours this water precipitates compounds which(although not acid) act as emulsifying agents and cause a high refiningloss. However, these compounds, with the watery meal, settle to thebottom and by drawing off about 10% of the oil and recentrifuging it,the watery meal, with such compounds, can be removed. This oil to bereoentrifuged can be mixed with the fresh oil and with it fed to thecentrifuge.

The watery meal discharged from the machine contains considerable oil,but by pumping it back and mixing it with the fresh meal going to thecooker this oil is recovered at the presses. The water added may varyfrom five to ten per cent. Somewhat more than enough water to be takenup in combination with the impurities should be added, but the additionof considerably more than that amount is inadvisable. An addition ofabout 6% is preferred.

Though the separation of meal from the oil can be accomplished in anyseparator that will continuously discharge solids from one outlet andliquids from another, I prefer to use a separator 50 of the constructionset forth in a patent issued to me December 3, 1935, No. 2,022,814,which has automatically operating valves controlling ports in theperipheral wall of the bowl.

In the accompanying drawing, which shows a 55 flow diagram of a plantusing my process: a is a crusher for cottonseed, b a cooker for crushedseed, 6 a press for squeezing out the 011, d a storage tank with anoutlet pipe having a valve 2. is a heater having an outlet, with a valveg, leading, through a strainer h, to a centrifugal separator i. a is awater tank having an outlet, with a valve It, also leading to thecentrifuge.

. From the centrifuge one outlet 1 discharges into a tank m, from whicha pump 11. discharges back to the cooker I), while the other outletdischarges l0 erally with the addition of a little water or steam, 2

at b. The meal is then put in blankets and placed under a hydraulicpress c, where the oil is squeezed out and flows to a storage tank d,where it is held for about 24 hours. From the storage tank the oil, at arate controlled by the valve e, 25 flows through the heater J, Where itstemperature is raised to about 110 F. It then flows through a strainerit that removes very coarse particles. The oil, containing the remainingfiner particles, flows toward the centrifugal separator 2'. On its 30way thereto it is mixed with suflicient water (from tank a) to sosaturate the meal as to make it enough heavier to be easily separatedfrom the oil and to make it fluid enough to flow out of the bowl. In theseparator the meal and water, 5 mixed together, are separated from theoil and discharged into the tank m, whence the pump n forces them backto the cooker. The nearly purified oil is discharged to the tank 0,whence the pump 12 forces it to one of the clean oil storage tanks q.After standing in these storage tanks for 12 hours or more the lowerportion (from five to fifteen per cent. of the whole, preferably about10% comprising oil containing watery meal and precipitated compounds, isslowly drawn off through a valve r to the heater 1, where it mixes withthe stream of fresh oil and is recentrifuged. The remainder of the oil,free of impurities, isdrawn off through the valve s for shipment.

What I claim and desire to protect by Letters Patent is: a

1. The process of purifying vegetable oil containing fine solids, whichcomprises flowing such oil toward a locus of centrifugation, flowingwater in much smaller rate toward the same locus and mixing it with theoil and substantially immediately, and before development of acids byreaction between the water and the solids, separating by centrifugalsubsidence a major portion of the water and solids together with a minorfraction of the oil from a major portion of the oil containing a smallpercentage of water and solids, subjecting the last named centrifugallyseparated constituent to gravity settlement so prolonged as to separatesaid constituent into an upper stratum containing the bulk of the oil ina substantially completely purified condition and a lower stratumcomprising an oil containing a small percentage of watery meal andprecipitated compounds, separating the upper stratum of purified oilfrom said lower stratum of oil containing watery meal and precipitatedcompounds and subjecting the last named oil to centrifugal subsidence.

2. The process defined in claim 1 in which the duration of the gravitysettlement is not less than twelve hours.

3. The process defined in claim 1 in which the percentage of water addedis within the range of about 5 to 10%.

4. The process set forth in claim 1 in which a fresh stream of oil to besubjected to the first centrifugal subsidence operation specified andthe last named oil containing a small percentage of watery meal andprecipitated compounds are fed to a common locus and centrifugedtogether.

5. The process set forth in claim 1 in which the water containing mostof the solids and some oil that is separated from the major portion ofthe oil in the centrifugal subsidence operation is mixed with fresh oilto be subjectedas specified to centrifugal subsidence.

6. The process of purifying vegetable oil containing fine solids, whichcomprises flowing such oil toward a locus of centrifugation, flowingwater in much smaller rate toward the same locus and mixing it'with theoil and substantially immediately, and before development of acids byreaction between the water and the solids, separating by centrifugalsubsidence a major portion of the water and solids together with a minorfraction of the oil from a major portion of the oil containing a smallpercentage of water and solids, subjecting the last named centrifugallyseparating constituent to gravity settlement so prolonged as to separatesaid constituent into an upper stratum containing the bulk of the oil ina substantially completely purified condition and a lower stratumcomprising an oil containing a small percentage of watery meal andprecipitated compounds, separating the upper stratum of purified oilfrom said lower stratum of oil containing watery meal and precipitatedcompounds, and 25 mixing with a stream of fresh oil flowing toward thelocus of centrifugate the said oil containing a small percentage ofwatery meal and precipitated compounds that has been separated byprolonged gravity settlement and the said mixture of water, solids and aminor fraction of oil that has been separated by centrifugal subsidence.

GEORGE J. STREZYNSKI.

